Volume 3 / Book 3 — CHAPTER XIV. INTO HOW MANY ZONES IS THE EARTH DIVIDED?
Reading edition
Pythagoras says that, as the celestial sphere is distributed into five zones, into the same number is the terrestrial; which zones are the arctic and antarctic, the summer and winter tropics (or temperate zones), and the equinoctial; the middle of which zones equally divides the earth and constitutes the torrid zone; but that portion which is in between the summer and winter tropics is habitable, by reason the air is there temperate.